The functional value of an object is its instrumental purpose. (A pen writes. A diamond ring adorns an otherwise empty hand.) This is what Marx referred to as the 'use-value' of the commodity.

The exchange value of an object is its economic value. (A pen is worth three pencils. A diamond ring is worth three months' salary.)

The symbolic exchange value of an object is its arbitrarily assigned and agreed value in relation to another subject. (A pen represents a graduation present or a speaker's gift. A diamond ring symbolizes a public declaration of love between two individuals.)

The sign exchange value of an object represents its value in a system of objects. (A pen is part of a desk set, or a particular pen confers social status. A diamond ring has sign exchange value in relation to other diamond rings, conferring social status to the person with the biggest or prettiest ring.)